Process and apparatus for controlling water in a dry cleaning solvent composition with a humidity responsive device



Jan. 3, 1961 R. J. REITZ 2,967,084

PROCESS AND APPARATUS FOR CONTROLLING WATER IN A DRY CLEANING SOLVENT COMPOSITION WITH A HUMIDITY RESPONSIVE DEVICE Filed July 1, 1952 56 IL .1: ..1. m 50 e/cfO/QF/Qf g0 49 H r F'Q' i I 4 I [I HI i J J I 35 1 1 22 I 15 57/ J 5556 l J'o la/l I I:

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' xFfiifTJ/TZ BY I @z; m/z/W nit-ed States Patent PROCESS AND APPARATUS FOR CONTROLLING WATER IN A DRY CLEANING SOLVENT COM- POSITIEN WITH A HUNHDITY RESPONSIVE DEVIC Robert J. Reitz, Pittsburgh, Pa., assignor, by mesne assignments, to Associates Discount Corporation, South Bend, Ind., a corporation of Indiana Filed July 1, 1952, Ser. No. 296,705

5 Claims. v (Cl. 8-142) This invention relates to the control of moisture in dry cleaning systems and more particularly to a method and apparatus for automatically controlling the relative humidity of the dry cleaning solvent in such a system. The term relative humidity as used herein designates the degree of saturation with respect to water of a dry cleaning solvent that is in equilibrium with atmospheric air of a given relative humidity. Otherwise stated, what is meant herein by the term relative humidity of the solvent is the amount of water dissolved in a dry cleaning solvent such as is used in the cleaning industry relative to the total amount of water the solvent is capable of dissolving, with or without the aid of solubility promoters such as soaps.

In a conventional dry cleaning operation the goods to be cleaned are washed in a rotating drum with a suitable organic solvent, e.g. a petroleum solvent such as the so-called Stoddard solvent, naphtha or perchlorethylene, which may or may not contain a soap. In the operation of such systems it has been found that if a small amount of water is dissolved or quickly dispersed in the cleaning solvent, the cleaning ability of the solvent is improved. However, it has also been found that the use of too much Water in the solver gives rise to a number of disadvantages. Thus if an excessive amount of Water is introduced into the solvent, the garments being cleaned by the solvent may lose their creases, become excessively wrinkled and shrink. Also there is some indication that excessive amounts of water may promote the re-deposition of soil on white or light-colored goods. Consequently, when water is to be added to the solvent to improve its cleaning ability, it is desirable that the amount of water in the solvent be maintained between predetermined limits.

It is accordingly a primary object of the present invention to provide a sensitive and accurate system for controlling the relative humidity of a dry cleaning solvent. It is another object of the invention to provide apparatus for injecting water into a dry cleaning solvent in an accurately controlled amount dependent upon the amount of water already present therein. It is still another object of the invention to provide apparatus for continuously determining the moisture content of a dry cleaning solvent in a continuously circulating solvent dry cleaning system. It is a further object of the invention to provide apparatus for adding water to a dry cleaning solvent in a dry cleaning system by injecting a solution that includes water and a suitable dispersing agent for improving the dispersion of the water in the cleaning solvent. It is a still further object of the invention to provide apparatus for instantaneously and continuously indicating the water content of a dry cleaning solvent in a dry cleaning system.

These and other and further objects will be in part pointed out and in part apparent as the specification proceeds.

In the drawings;

off valve 29 and a solenoid control valve 32. to an in- Figure 1 is a diagrammatic representation of a dry cleaning system including the conventional washer, lint trap, pump and filter, and provided with control apparatus embodying the present invention.

Figure .2 is an. enlarged detailed diagrammatic view of the humidity sensing device of the moisture control apparatus of Figure 1; and,

Figure 3 is a view similar to Figure 2 of an alternative sensing element that may be substituted for the apparatus of Figure 2.

The method of the present invention is escepially useful in dry cleaning systems wherein solvent is continuously withdrawn from the washer during the washing operation, passed through a filter to filter from the sol- ,vent suspended matter-that has been removed from the goods being washed, and then returned to the Washer. In one of its broader aspects the present method comprises measuring the relative humidity of the recirculated solvent, :and supplying water to the solvent in controlled amounts that are related to the measured value of the relative humidity to maintain the water content of the recirculated solvent substantially at a desired value. I have found that by controlling the relative humidity or degree of water saturation of the solvent, the desired improvement in the cleaning abilityof the solvent can be attained and at the same time the Water content of the goods being washed can be brought substantially to a predetermined desired value, even though the moisture condition of the goods as charged into the washer may vary. Thus by using the present method, goods may be etficiently washed and at the same time conditioned to a desired moisture content for the subsequent pressing step.

Referring now to the drawings and more particularly to Figure 1 there is shown a conventional dry cleaning system having a washer 1% in which the goods are agitated in a dry cleaning solvent by being'rotated in a perforated drum that is partially immersed in the solvent. Tne solvent is withdrawn from the washer it) through a pipe 12 and lint trap 14 by a pump 16 and then pumped into a filter 18 which removes suspended matter from the solvent. The filtered solvent is then returned from the filter to the washer through a pipe 29.

In addition, according to the present invention there is provided a humidity sensing apparatus 21, a water injector 24 and a transducer assembly 26 through which the sensing device is adapted to control the water injector. Water from a suitable source such as a water main is supplied through a pipe 28 containing a shutjector nozzle 24. In the preferred embodiment of Figure 1 the injector nozzle 24 is located at the intake of the pump 16 so as to take advantage of the beneficial dispersing action thereof obtained in the normal circulation of .the cleaning solvent.

In certain installations, as will be explained in detail hereafter, it is desirable to admit water to the system from a container 30 of stock solution through a shutoff valve 31 and thence through the control valve 32 to the injector nozzle 24.

The orifice of the injector 24 is so chosen that good dispersion of the water or solution will be obtained in the cleaning fluid. It has been found that good dispersion will be obtained when the diameter of the orifice is made as small as possible consistent with the desired delivery rate and the available pressure so that maximum possible velocity of the entering jet of the Water is realized. Excellent dispersion can also be achieved by using special nozzles, such for example as the so-called pin jet nozzle.

Located close to the pump discharge and ahead of the filter in the direction of flow of the solvent is a side stream diverting pipe 34 which conducts a sampling stream to a disengaging chamber 22 and then through a trap 36 back to the washer drum.

As may be seen more clearly from Figure 2 the humidity sensing apparatus comprises a gas-entraining jet injector 38, a disengaging chamber 22, and a humidity testing element 44. The injector 38 comprises a solvent noZZle 39 disposed in the entrance to discharge pipe 41 and a chamber 43 surrounding the nozzle and pipe and having an inlet opening 45 therein for admission of an inert gas, preferably air. Pipe 4-1 extends downwardly and transversely of chamber 22 and discharges the solvent and entrained air into it. The air is thus intimately mixed with the cleaning solvent in the entraining and discharging, thus resulting in equilibrium being attained between solvent and air as to their respective water contents, which is further aided by disengaging chamber 22 itself.

The equilibrated air then passes upward through a pipe 51 into a chamber 46 and out through an orifice 42. The air leaving orifice 42 may be discharged to the atmosphere if desired, but is preferably returned to the intake 45 of the injector 38 through a pipe 47 provided with a breather vent 49. The disengaged cleaning solvent flows to the bottom of the chamber 22 and into the trap 36 which provides a liquid seal against the escape of air into the washer drum. A vent 35 is provided on the trap 36 to prevent the liquid from being siphoned completely out of it once flow is initiated, thus preventing the loss of the liquid seal.

Enclosed in chamber 40 well within the stream of separated air is an electrical humidity testing element 44. This element may be of any well known type such as that which employs an electrically conductive film containing lithium chloride and is so made that the electrical resistance of the film varies as a function of the humidity of the atmosphere to which it is exposed. Suitable elements of this type are commercially available.

It is important that the relative humidity of the equilibrated air remain unchanged between the time it becomes disengaged from the solvent and the time when it comes in contact with element 44. Hence the pipe 51 and chamber 40 should be carefully insulated to minimize heat loss by the equilibrated air. Alternatively the chamber 40 and pipe 51 can be provided with a jacket through which the solvent passes before entering injector 38.

The hygrometer unit 44 is connected to the transducer 26 which converts the hygrometer signal into a control voltage sufficient to actuate the solenoid valve 32. The transducer 26 is effectively an electrical circuit which measures the resistance of the lithium chloridebearing film of the sensing element and actuates an onoif electrical relay at a given value of resistance. It may be any suitable detector-amplifier-relay combination such as are commercially available. The output of the transducer is used to actuate the solenoid valve 32. which in turn regulates the admission of water to the cleaning solvent through the injector 24.

There is thus provided a sensitive, instantaneous and continuous indication of the relative humidity of the dry cleaning solvent together with apparatus for controling the relative humidity thereof, making it possible to improve the cleaning qualities of the solvent the desired amount without excessively increasing the water content of the goods being washed.

The apparatus is provided with alternative sources of water, the choice of which depends upon the type of cleaning solvent used in the particular dry cleaning system. If the dry cleaning solvent, either of itself or because it contains additives, has a sufficiently high solvent power or capacity for water, the water may be taken directly from the ordinary domestic supply line at line pressure as indicated at 28. If however, the solvent does not have sufficient solvent power for water, a solution is supplied from a tank 30 which is filled with a mixture of water and emulsifier or with a prepared emulsion of water, solvent, and emulsifier called stock solution. This liquid is then placed under pressure by, for instance, compressed air and injected into the cleaning solvent through the injector 24 under the regulation of valve 32, valves 29 and 31 being shut and open respectively.

In Figure 3 is shown an alternative type of humidity sensing element that may be substituted for the apparatus enclosed within the dotted line in Figure 1. This type of element is known as a dimensional-change sensing element. In general, the active element of this type of hygrometer can be placed directly in the solvent without damage and changes in its dimensions with changes in the water content of the solvent. In the particular embodiment shown, hair is the sensing element, although other materials, such as wood, which are well known for hygrometric application, can be used.

In Figure 3 the hair assembly 47 is connected, through a fluid seal bellows 49, by a rod 51, to one arm of a bellcrank lever 53 pivoted at 58. This arm is biased by spring 55 in the upward position so that the contact 57 on the end of the other arm is in the open position. When there is insuflicient water present in the solvent as it passes about the hair the rod 51 is pulled downward, pivoting lever 53 so that contact 57 meets contact 59 closing the circuit to the transducer 26 which in turn actuates the solenoid valve 32.

It should be noted that the deviec of Figure 3 can be more readily arranged in the main solvent stream, thus obviating the necessity for a sampling stream such as is shown in Figure 1. With this type of element the transducer may be a simple mechanically-operated electrical contact which controls the solenoid valve 32 either directly or through an intermediate stage.

In Figure l is shown a preferred arrangement for the injection and sampling of the solvent stream. However it is to be understood that the particular locations shown are not the only ones that may be used. For example, the solvent may have insuffic-ient solvency for water to transfer practical amounts of the latter to the washer except as a coarse emulsion, and in this case it would be unwise to pass the solvent through the filter. Consequently the water injector should then discharge into the solvent return line 20 after the filter and before the washer or else directly into the washer drum itself.

This should be contrasted with the so-called charged" solvent system wherein larger concentrations of chemical additives are used and it is possible to realize a relatively high solubility of water in the solvent. In cases of this type, water injection at the point shown in Figure 1 is possible, without interference by or to the filtration, and thus the system is able to take advantage of the strong dispersing action of the solvent pump 16.

In addition the location of the sensing element and the moisture injector as shown in Figure 1 is advantageous in that measurement of the amount of added water is obtained almost immediately after it is injected thus preventing overshooting of the humidity control point. A reversal of the locations shown in Figure l is possible but the lag between the water injection and measurement would have to be taken into account.

In many dry cleaning installations the operator uses what is known as a batch run process in which the washing program is started with a load of garments in the drum with no circulation of solvent through the customary filters and so forth. In a system where it is desired to use this type of operation a by-p-ass 50 (Figure 1) can be placed between the pump discharge and the return line 20 to the washer drum with appropriate valves 52, 54 and 56 to prevent fiow through filter 18. Thus during batch run operations valves 52 and 56 would be closed and valve 54 opened with the rest of the apparatus functioning as described above. The solvent would then be circulated through the moisture control apparatus and directly back to the Washer drum providing the desired control in batch run operation.

Since many embodiments might be made of the present invention and since many changes might be made in the embodiments disclosed herein, it is to be understood that the foregoing description is to be interpreted as illustrative only and not in a limiting sense.

I claim:

1. In a dry cleaning process of the type wherein goods are washed in the rotatable drum of a washer by a dry cleaning solvent composition, said solvent composition is withdrawn from the washer, pumped through a filter and recirculated to the washer in a continuous circulating path, and said solvent composition initially contains a predetermined amount of water which is less than the water saturation value for said composition and less than the amount which would cause undesirable shrinkage of said goods, the steps of maintaining the water content of said solvent at a desired value suflicient to remove water-soluble stains from said goods without producing undesirable shrinkage thereof which comprise, withdrawing a continuous sample of said circulating solvent composition, mixing said solvent composition with a stream of air to equilibrate the water content of the solvent composition and the air mixed therewith, separating the equilibrated air from the solvent composition, measuring the relative humidity of the separated air, supplying water to the circulating solvent composition and regulating the supply of water to the solvent in response to variations in the measured relative humidity of said separated air so that the water content of said solvent composition is maintained at said desired value.

2. A method according to claim 1 and wherein the withdrawn sample of circulating solvent composition is continuously returned to said circulating path.

3. A method according to claim 1 and wherein the equilibrated air is continuously recirculated for mixing with an unequilibrated portion of said continuous sample.

4. In a dry cleaning apparatus of the type wherein the goods to be cleaned are washed in a rotatable washing drum and a dry cleaning solvent composition is circulated by a pump through said drum and a filter in a closed circulating path, apparatus for supplying a controlled amount of water to said system comprising, in combination, water supply means connected to said path and including flowregulating means for regulating the flow of water to said path; a humidity measuring device, flow diverting means interconnecting said circulating path and said measuring device to divert a small stream of the circulating solvent composition to said device, said humidity responsive device comprising mixing means for mixing the diverted stream of solvent with a stream of atmospheric air to equilibrate the water contents of the solvent and air, a sep arating chamber for separating the equilibrated solvent and air, and a humidity responsive device positioned in contact with the separated equilibrated air; and transducer means actuated by the output of said humidity responsive device and connected to said regulating means to regulate the flow of water to said circulating solvent.

5. Apparatus according to claim 4 and wherein said 'water supply means is connected to said circulating path near the inlet of said pump and said flow diverting means is connected to said circulating path near the discharge of said pump.

References Cited in the file of this patent UNITED STATES PATENTS 1,388,613 Simsohn Aug. 23, 1921 1,911,289 Reddish May 30, 1933 2,024,981 Reddish Dec. 17, 1935 2,056,141 Myers Sept. 29, 1936 2,158,614 Reddish May 16, 1939 2,400,431 Mabey May 14, 1946 2,490,634 Keene Dec. 6, 1949 2,540,431 Davis et al Feb. 6, 1951 2,614,026 Lascari Oct. 14, 1952 2,621,673 Hodgens Dec. 16, 1952 2,622,967 Lobosco Dec. 23, 1952 FOREIGN PATENTS 435,575 Great Britain Sept. 24, 1935 OTHER REFERENCES Natl. Inst. of Drycleaning, Silver Spring, Md., Bull. No. T-309, July 31, 1953 (2 pp.) 

1. IN A DRY CLEANING PROCESS OF THE TYPE WHEREIN GOODS ARE WASHED IN THE ROTATABLE DRUM OF A WASHER BY A DRY CLEANING SOLVENT COMPOSITION, AND SOLVENT COMPOSITION IS WITHDRAWN FROM THE WASHER, PUMPED THROUGH A FILTER AND RECIRCULATED TO THE WASHER IN A CONTINUOUS CIRCULATING PATH, AND SAID SOLVENT COMPOSITION INITIALLY CONTAINS A PREDETERMINED AMOUNT OF WATER WHICH IS LESS THAN THE WATER SATURATION VALUE FOR SAID COMPOSITION AND LESS THAN THE AMOUNT WHICH WOULD CAUSE UNDESIRABLE SHRINKAGE OF SAID GOODS, THE STEPS OF MAINTAINING THE WATER CONTENT OF SAID SOLVENT AT A DESIRED VALUE SUFFICIENT TO REMOVE WATER-SOLUBLE STAINS FROM SAID GOODS WITHOUT PRODUCING UNDESIRABLE SHRINKAGE THEREOF WHICH COMPRISE, WITHDRAWING A CONTINUOUS SAMPLE OF SAID CIRCULATING SOLVENT COMPOSITION, MIXING SAID SOLVENT COMPOSITION WITH A STREAM OF AIR TO EQUILIBRATE THE WATER CONTENT OF THE SOLVENT COMPOSITION AND THE AIR MIXED THEREWITH, SEPARATING THE EQUILIBRATED AIR FROM THE SOLVENT COMPOSITION, MEASURING THE RELATIVE HUMIDITY OF THE SEPARATED AIR, SUPPLYING WATER TO CIRCULATING SOLVENT COMPOSITION AND REGULATING THE SUPPLY OF WATER TO THE SOLVENT IN RESPONSE TO VIRIATIONS IN THE MEASURED RELATIVE HUMIDITY OF SAID SEPARATED AIR SO THAT THE WATER CONTENT OF SAID SOLVENT COMPOSITION IS MAINTAINED AT SAID DESIRED VALUE.
 4. IN A DRY CLEANING APPARATUS OF THE TYPE WHEREIN THE GOODS TO BE CLEANED ARE WASHED IN A ROTATABLE WASHING DRUM AND DRY CLEANING SOLVENT COMPOSITION IS CIRCULATED BY A PUMP THROUGH SAID DRUM AND A FILTER IN A CLOSED CIRCULATING PATH, APPARATUS FOR SUPPLYING A CONTROLLED AMOUNT OF WATER TO SAID SYSTEM COMPRISING, IN COMBINATION, WATER SUPPLY MEANS CONNECTED TO SAID PATH AND INCLUDING FLOWREGULATING MEANS FOR REGULATING THE FLOW OF WATER TO SAID PATH; A HUMIDITY MEASURING DEVICE, FLOW DIVERTING MEANS INTERCONNECTING SAID CIRCULATING PATH AND SAID MEASURING DEVICE TO DIVERT A SMALL STREAM OF THE CIRCULATING SOLVENT COMPOSITION TO SAID DEVICE, SAID HUMIDITY RESPONSIVE DEVICE COMPRISING MIXING MEANS FOR MIXING THE DIVERTED STREAM OF SOLVENT WITH A STREAM OF ATMOSPHERIC AIR TO EQUILIBRATE THE WATER CONTENTS OF THE SOLVENT AND AIR, A STEPARATING CHAMBER FOR SEPARATING THE EQUILIBRATE SOLVENT AND AIR, AND A HUMIDITY RESPONSIVE DEVICE POSITIONED IN CONTACT WITH THE SEPARATED EQUILIBRATED AIR; AND TRANSDUCER MEANS ACTUATED BY THE OUTPUT OF SAID HUMIDITY RESPONSIVE DEVICE AND CONNECTED TO SAID REGULATING MEANS TO REGULATE THE FLOW OF WATER TO SAID CIRCULATING SOLVENT. 